DE102009042819A1 - Sprag - Google Patents

Abstract

A clamping body freewheel includes an inner ring, an outer ring rotatable relative to the inner ring in at least one direction of rotation, a cage for clamping bodies between the inner ring and the outer ring and a plurality of clamping bodies, wherein the clamping bodies between a clamping position, in which they prevent a relative rotation between the inner and outer ring, and a release position in which they allow a relative rotation between the inner and outer ring, can be tilted, wherein a Klemmkörperanfederung is provided which biases the clamp body radially inwardly and in the direction of clamping position, wherein the Springs Klemmfeder is provided as separately for each clamp body spring.

Description

The The invention relates to a sprag freewheel, in particular a damped sprag freewheel with cage, for example, on the output side of a crank-CVT transmission is usable, as well as a crank-CVT transmission with such Sprag.

A crank-CVT transmission is for example from the EP 1 650 071 A2 known. On an input shaft driven by a motor which forms a driving shaft with respect to the gear, there is provided an eccentric cam variable displacement drive assembly which is connected via connecting rod-like connecting elements to a driven shaft forming an output or output shaft with respect to the transmission , By transmitting the stroke of the connecting elements by means of freewheel devices on the driven shaft and thus the output side of the transmission, the driven shaft is driven to rotate. The freewheel devices are provided between the connecting rod-like connecting elements and the driven shaft.

In This crank CVT transmission are the driving crankshaft and the output shaft or driven shaft aligned parallel to each other and rotatably mounted in the transmission housing. If from one Internal combustion engine torque is introduced into the crankshaft, the torque is transmitted to the output shaft through the crank CVT transmission. Depending on the position of the eccentric components with respect to the axis of rotation the drive shaft is the eccentricity of Exzenterbauteile and thus changes its axis of rotation relative to the drive shaft, whereby the transmitted from the connecting rod-like connecting elements to the output shaft Stroke and thus set the gear ratio can be. On the output shaft, for example, the torque be tapped for driving wheels of a vehicle. As a rule, in the axial direction of the crank-CVT transmission Crankshaft arranged one behind the other several eccentric units, at each of which connecting rod-like connecting elements are attached and those with a corresponding number of freewheel units the output side of the transmission communicate on the Output shaft also arranged in the axial direction one behind the other are.

For The freewheels are basically two types of Freewheeling known, namely reversible, freewheels, depending on their switching position optionally the relative rotation of a Block the outer ring and an inner ring in one of the two directions of relative rotation, and those that are fixed and unchangeable Blocking direction in which they have a relative rotation between prevent an outer ring and an inner ring while in the other direction of relative rotation, the rotation of the outer ring and the inner ring is allowed relative to each other. With reversible Freewheeling has to, for example, a reverse gear to realize, no additional gear or a separate Motor are provided, as by switching the freewheels the direction of rotation of the output shaft relative to the input shaft of the gearbox can be changed. For non-switchable Freewheeling is either a separate engine, for example an electric motor, provided or it will be connected to the output shaft the transmission downstream of another transmission, for example Planetary gear, coupled when needed, namely, then when a reverse function is provided is, is part of the load transfer path in the transmission and otherwise disconnected.

switchable Freewheels are commonly used as roller freewheels designed where rollers between the inner ring and the outer ring unroll and by suitable springing in a nip in a or the other direction of relative rotation. To is at least one of the inner ring or the outer ring profiled so that the mentioned nip is generated.

alternative For roller freewheels are sprag clutches known, the more compact and lighter than roller freewheels are. These are z. B. the clamping body profiled so, that in one position the relative rotation of the inner and outer rings, which can have both circular cross section, block and in another position allow the relative rotation.

at the freewheels that position of the clamping or Rolling body in which the clamping or rolling body Make sure that the inner ring and the outer ring block each other, referred to as a clamping or locking position, in the rolling or clamping body in a between inner ring and outer ring formed clamping gap. The position, in they make a twist of the inner ring and the outer ring allow each other is referred to as freewheeling position. These Terminology is also used in the present specification for such (sprag) freewheels used in which the blocking or release of a currently effective seeds Diameter of the clamp body and not the position of the clamp body along the circumferential direction depends.

It Object of the invention, a sprag freewheel, in particular for a crank-CVT gearbox, which has a sturdy construction is working and reliable.

This object is achieved with a sprag freewheel with the features of claim 1. Preferred embodiments are given in the dependent claims. In claim 17, a crank-CVT transmission is defined which uses such a sprag freewheel.

Of the Invention is based on the idea of a freewheel with clamping bodies provide that by their profile in a cross-section perpendicular to the axial direction of the freewheel are designed such that they by rolling on the inner ring a clamping position or a freewheeling position can take depending on their tilt position, the single clamp body in a cage, the between the inner ring and the outer ring is provided, held and be guided and on the cage for everyone Clamping element individually and separately a sprag suspension is provided. The tilted position thus defines an effective Diameter of the clamping body, depending on the tilted position changed. Due to the separate sprag spring suspension can the force direction and size by appropriate Choice of spring constants and the effective direction of the force chosen Be that geometric tolerances are barely on the height the effective force and in addition to a basic pressure for each clamp body, giving a quick reset to ensure movement in the nip, a part the energy present in the movement out of the nip Friction can be destroyed or in the Klemmkörperanfederungen can be saved to a quick turn back the clamping body at the end of the damping process, d. H. back in the nip, to ensure. Thus, can through the individual Klemmkörperanfederungen for each one of the clamp body a reliable Operation of the freewheel can be ensured. Furthermore can by a direction of action of the force, which is a component radially inwardly, by the Einzelklemmkörperanfederung Ensures the installation of the clamping body on the inner ring in any operating condition become.

To a preferred embodiment, the inner ring and the outer ring in a section perpendicular to the axial direction the freewheel each circular. This is the production the inner ring and the outer ring easy. This is going through the use of sprags with profile (in one cut perpendicular to the axial direction), the profiling the clamp body of the shape is that they are in a tilted position allow the rotation of the inner ring and the outer ring to each other, d. H. that between the clamp body and example the outer ring is air when the clamp body on Inner ring is applied. In the other tilt position is the twist blocked the inner ring and the outer ring to each other, what then the case, if the clamp body at the same time clamped on the inner and outer ring.

Preferably the cage is rotatable on the inner ring. Next is preferably a cage spring provided such that they put the cage against the inner ring and / or one with the Inner ring preloaded firmly connected component. This means that at a rotation of the cage relative to the Inner ring friction energy is generated, so that the movement of the clamping body from the nip and the cage opposite the inner ring is damped and energy is destroyed.

For example For this purpose, the outer ring on the inner ring can be replaced by a or rolling bearings and the sliding or rolling bearing be set on the inner ring, preferably be pressed. The cage spring can then cage in axial Direction against one of the bearing rings of the sliding or rolling bearing tense.

To A preferred embodiment is the cage spring suspension formed by a disc spring, which is overall simple in construction is.

Preferably are the springs of sprag suspension on the cage stored, which in turn offers advantages in assembly, as the cage with the Klemmkörperanfederungsfedern as assembly in advance can be trained and then with inner and outer rings and the clamping bodies can be mounted.

advantageously, are the springs of sprag suspension as Schenkel or Leaf springs designed, preferably with relatively smaller Spring constant. Thus, on the one hand, the pressing direction or effective direction the feathers are set well and, on the other hand, geometric ones Tolerances hardly due to the small spring constant on the height which actually applied to the clamp body Power out.

The Clamp body springing force is preferably chosen such that that the radial component of the sprag impact force, d. H. the component of the force acting in the radial direction of the freewheel acts, greater than a maximum centrifugal force of the respective clamping body is. This allows the clamp body reliably pressed against the inner ring in every operating condition so that the lifting of the clamp body from the inner ring is reliably prevented in any operating condition.

Preferably the center of gravity of the individual clamping body is in radial Direction radially outside a guide area for the clamping body, which is provided on the cage is. As a result, the tilting or rolling movement of the clamping body be performed reliably and easily on the inner ring and is hardly influenced by leadership areas on the cage.

To a preferred embodiment is the cage designed such that for each clamp body on Cage a stop is provided, with a corresponding shaped portion of the clamp body can interact, so that a movement distance of the clamp body at its Motion is limited from the clamping position to the free-running position is, thereby preventing the clamp body from the cage or too far away from the nip reach. As a result, a failure of the freewheel can be prevented or a reliable and fast switching between clamping position and free-running position are ensured.

Preferably are the clamp body in the cage with play guided and shaped with respect to the inner ring, that the clamping bodies can roll on the inner ring, without the cage shifts or the clamp body on the inner ring or the cage must slide. These are Contours of a cage and the slider, preferably coordinated so that the contour of the cage in the Guide area has a shape of the rolling curve of the profile corresponds, d. H. is congruent, but to a certain, minor game moved in parallel is. Thus, the clamp body when unrolling always the same, little game to the cage. This will ensure that in the freewheel not unnecessarily energy is destroyed and friction and thus heat is generated, if necessary must be dissipated.

To a preferred embodiment is the outer ring the freewheel with a connecting rod eye for connection to a connecting rod-like Configured connecting element of a crank CVT transmission. The connecting rod-like Connecting element provides the connection to the drive side of the transmission ago.

To a preferred embodiment are adjacent to the Connecting rod one or more voltage reduction through holes or Relief breakthroughs provided. This can be a failure or a breaking or tearing of the outer ring in Area of the connecting rod to be avoided, as such relief breakthroughs significantly reduce the stresses in the area of the connecting rod eye.

following the invention will be described by way of example with reference to the attached Figures described in which:

1 a cross-sectional view through a freewheel according to the invention in a direction perpendicular to the axial direction of the freewheel;

2 a cross-sectional view in the axial direction by the freewheel according to 1 is;

3 a section of the in 1 illustrated freewheel is, the freewheel is not cocked;

4 a view accordingly 3 is, but the freewheel is stretched;

5 a view accordingly 3 and 4 is, with the help of which the damping process is explained;

6 an enlargement of the view according to 2 is;

7 represents a first embodiment of the outer ring; and

8th shows a second embodiment of the outer ring.

1 shows in a cross section in a direction perpendicular to the axial direction and 2 in cross-section in the axial direction a sprag freewheel 10 according to an embodiment of the invention. Details of the views according to 1 and 2 are in 3 to 5 respectively. 6 shown.

The damped sprag freewheel 10 contains an inner ring 12 and an outer ring 14 having a common axis of rotation A and are concentric with each other. The inner ring 12 has a cross section in 1 circular outer surface 13 , The outer ring 14 has a cross section in 1 circular inner surface 15 ,

The inner ring 12 For example, it may be identical to the output shaft of a crank-CVT transmission or it may be connected with it in a torque-proof manner or via a transmission as required. The outer ring 14 is as a circular ring with a bulge 16 provided radially outward, wherein in the region of the bulge 16 a connecting rod eye 18 is integrated. About the connecting rod eye 18 can be made by means of, for example, connecting rod-like connecting elements (not shown), a connection to the drive side of the crank-CVT transmission, so that the stroke generated by the eccentric units on the connecting rod-like connecting elements on the outer ring 14 is transmitted and the rotation of the outer ring 14 leads.

In 1 is also a voltage reduction through hole 19 in the area of the connecting rod eye 18 , ie adjacent, recognizable. The stress reduction through hole 19 is in the in 1 illustrated embodiment as substantially in the tangential direction of the connecting rod eye 18 or the inner surface 15 of the outer ring 14 elongated opening designed, whose the connecting rod eye 18 facing side of the shape of the Pleuelauges follows, so that the voltage reduction through hole 19 is tapered towards its edge regions in a middle region seen in the tangential direction.

7 shows the outer ring 14 out 1 and 2 in detail. In 8th is an alternative embodiment of the outer ring 14 , in particular the voltage reduction passage openings 19 ' shown, wherein in this embodiment, two separate stress reduction through holes in the area adjacent to the bulge 16 of the outer ring 14 are provided. The stress reduction through holes 19 respectively. 19 ' relieve the bulge 16 so that stresses are reduced in this area. For this purpose, the voltage reduction through openings are preferably configured overall as passage openings or discharge openings, but blind holes are also possible in principle.

How best in 2 and 6 it can be seen, is the outer ring 14 on the inner ring 12 via a plain bearing 20 stored. The plain bearing 20 is on the inner ring 12 or the output shaft pressed firmly. The outer ring 14 is thus relative to the inner ring 12 rotatably mounted. This will between the inner surface 15 of the outer ring 14 and the outer surface 13 of the inner ring 12 an annular gap 21 educated. In this annular gap 21 are clamp bodies 22 brought in through a cage 24 be guided. The cage 24 is also rotatably mounted on the inner ring and thus can be in abutment. Besides, he will, like 6 is removable, by a plate spring 26 preloaded in the axial direction. The plate spring 26 thus forms with a cage spring suspension. This will be the cage 24 through the plate spring 26 against the in 6 left bearing ring of the plain bearing 20 pressed. Since the bearing rings of the plain bearing 20 to the inner ring 12 are fixed and against rotation, thus resulting in a rotation of the cage 24 opposite the inner ring 12 or the plain bearing 20 Friction, so when twisting the cage 24 Friction energy is destroyed.

As 6 can be removed, a bearing ring of the plain bearing 20 each for in the axial direction adjacent outer rings 14 be used together when the bearing surface of the plain bearing 20 is formed according to the outer ring, so that on a bearing ring of the sliding bearing 20 , as in 6 recognizable, two storage areas 23 are each formed for one of two adjacent outer rings.

Below are the cage 24 as well as the springing of the clamp body 22 described in detail, in particular 3 to 5 Reference is made.

The clamp body 22 each have a rolling surface 30 on, with which they are on the inner ring 12 can roll without gliding on it. By rolling on the inner ring 12 , in particular the outer peripheral surface 13 of the inner ring 12 with the rolling surface 30 The clamp body can be between the in 3 shown unstrained position of the freewheel 10 and the in 4 shown cocked position of the freewheel 10 move.

The cage 24 is with guide surfaces 40 respectively. 41 provided, which are shaped such that during movement of the clamping body 22 between the unstressed and the cocked position of the freewheel always a uniform game between the contour surface of the clamp body 22 and the guide surface 40 respectively. 41 of the cage 24 is present, so that the cage 24 does not shift or influence. That means the guide surfaces 40 . 41 essentially the rolling contour of the nose-shaped sprag areas 31 . 32 match, but are shifted parallel to these, so always the same game between cage 24 and clamp body 22 is present. At the in 3 illustrated unstressed position of the freewheel, wherein the clamping body 22 with respect to a tangent to the inner ring 12 at the point of contact of the clamp body 22 tilted to the right (clockwise) are the clamp body 22 with game to the inner surface 15 of the outer ring 14 ,

The cage 24 also has a stop for each clamp body 42 in the form of a stop lug, with which the nose-like area 31 of the clamp body 22 can get into contact when the clamp body 22 moved from the cocked position to a release position, while the movement of the clamp body 22 (ie an excessive tilting) can limit.

At the cage 24 are for each clamp body 22 each individual torsion springs 50 provided as sprag suspension. The thigh springs 50 practice on the clamp body 22 a radially inward and in the direction of clamping position (to the left in 3 ) directed Grundanpresskraft F _G from. The Grundanpresskraft F _G thus acts obliquely in the direction of the gap and radially inward. The tangential component of the basic contact force F _GT is chosen so that it forms the basic suspension in the direction of clamping position or clamping gap, ie that always sufficient basic suspension of the clamp body 22 Direction nip is provided. The radial component F _{GR of} the basic contact force F _G is preferably selected such that it is smaller than the maximum centrifugal force occurring during operation on the clamping body 22 is and thus the lifting of the clamp body 22 from the inner ring 12 prevented. The thigh feather 50 preferably has a relatively small spring constant, so that geometrical tolerances, for example when installing the leg springs 50 on the cage 24 or the clamp body 22 hardly itself to the Grundanpresskraft F _G impact.

In the in 4 shown clamping position, which schematically by an overlap of the outer ring 14 and the clamp body 22 is shown, is the clamp body 22 opposite to the 3 shown position tilted to the left and thus jammed the inner ring 12 and the outer ring 14 to each other. In the counterclockwise direction in 4 can the inner and outer ring 12 respectively. 14 thus only be twisted together.

If, as in 5 shown, the clamp body 22 Turning out of the nip at high speed, it tilts in the clockwise direction so far that the torsion spring 50 einfedert and an air gap 52 between the inner surface 15 of the outer ring 14 and the clamp body 22 arises. The thigh feather 50 thus absorbs a (small) part of the energy that is generated during the rotation of the clamp body 22 arises from the nip. This stored energy in the leg spring 50 is used at the end of the damping process to turn back the clamp body 22 in the direction of nip and thus the in 3 used position shown.

When moving from the clamping position to the freewheeling position, the clamping body rolls 22 also on the outside surface 13 of the inner ring 12 with its rolling surface 30 as long as the stop lug 31 of the clamp body 22 in abutment against the stop 42 on the cage 24 arrives. This causes an impulse force F _I on the cage, leading to a movement of the cage 24 opposite the inner ring 12 or with the inner ring 12 connected plain bearings 20 can lead. This cage movement is due to the friction between the slide bearing 20 and the cage 24 dampened by dissipating energy through friction. The resulting reaction force F _IR on the clamp body 22 generates a braking force F _IRB in the form of a frictional force and thus also deprives the system of energy. This will change the movement of the clamp body 22 from the nip by stop on the stop 42 of the cage 24 limited and any vibrations are damped by the frictional forces, so that the clamping body 22 quickly and reliably back to the 3 return home position shown and can be reliably brought from there into the clamping position. By the movement of the cage 24 also arises between the other nose-like sprag area 32 of the clamp body 22 and the corresponding guide surface 41 on the cage also a frictional force F _K , the vibration of the clamping body 22 attenuates.

10

Sprag

12

inner ring

13

outer surface

14

outer ring

15

palm

16

bulge

18

connecting rod

19

Stress reduction through opening

19 '

Stress reduction through opening

20

bearings

21

annular gap

22

clamping bodies

23

Lagerfäche

24

Cage

26

Belleville spring

30

rolling surface

31

Clamp body area

32

Clamp body area

40

guide surface

41

guide surface

42

attack

50

Leg spring

52

air gap

A

axis of rotation

F _G

basic contact

F _GT

tangential component of the basic contact force F _G

F _GR

radial component of the basic contact force F _G

F _I

impulsive force

F _IR

reaction force

F _IRB

frictional force

F _K

friction force

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• EP 1650071 A2 [0002]

Claims (17)

Sprag freewheel ( 10 ), containing an inner ring ( 12 ), one relative to the inner ring ( 12 ) in a first direction of rotation rotatable outer ring ( 14 ), a cage ( 24 ) for sprags ( 22 ) between the inner ring ( 12 ) and the outer ring ( 14 ) and a plurality of clamping bodies ( 22 ), wherein the clamping body ( 22 ) between a clamping position in which a relative rotation between the inner and outer ring ( 12 . 14 ) in a second direction of rotation, and a release position in which they a relative rotation between inner and outer ring ( 12 . 14 ) in the first direction of rotation, are tiltable, with a sprag suspension is provided, which the clamping body ( 22 ) biased radially inwardly and in the direction of the clamping position, wherein the sprag suspension as a separately formed spring for each clamping body ( 50 ) is provided. Sprag freewheel ( 10 ) according to claim 1, characterized in that an outer surface ( 13 ) of the inner ring ( 12 ) and an inner surface of the outer ring ( 14 ) in a section perpendicular to the axial direction in each case have a circular cross-section. Sprag freewheel ( 10 ) according to one of the preceding claims, characterized in that the cage ( 24 ) on the inner ring ( 12 ) is rotatable. Sprag freewheel ( 10 ) according to claim 3, characterized in that a cage spring ( 26 ) is provided, the cage ( 24 ) against the inner ring ( 12 ) and / or one with the inner ring ( 12 ) firmly connected component ( 20 ) preloaded. Sprag freewheel ( 10 ) according to one of the preceding claims, characterized in that the outer ring ( 14 ) on the inner ring ( 12 ) by a sliding or rolling bearing ( 20 ) is stored. Sprag freewheel ( 10 ) according to claim 5, characterized in that the sliding or roller bearing ( 20 ) on the inner ring ( 12 ), preferably pressed on, is. Sprag freewheel ( 10 ) according to claim 3 and claim 5 or 6, characterized in that the cage spring suspension ( 26 ) the cage ( 24 ) in the axial direction against a bearing ring of the sliding or rolling bearing ( 20 ) braced. Sprag freewheel ( 10 ) according to claim 7, characterized in that the cage spring suspension by a plate spring ( 26 ) is formed. Sprag freewheel ( 10 ) according to one of the preceding claims, characterized in that the springs ( 50 ) of the sprag suspension are mounted on the cage. Sprag freewheel ( 10 ) according to one of the preceding claims, characterized in that the springs of Springs Klemmfeder as leg or leaf springs ( 50 ) are designed. Sprag freewheel ( 10 ) according to any one of the preceding claims, characterized in that the radial component of the sprag abutting force (F _GR ) is greater than a maximum centrifugal force of the respective sprag ( 22 ). Sprag freewheel ( 10 ) according to one of the preceding claims, characterized in that the center of gravity of the clamping body ( 22 ) each radially outside a guide region ( 40 . 41 ) for the clamping body ( 22 ) on the cage ( 24 ) lies. Sprag freewheel ( 10 ) according to one of the preceding claims, characterized in that on the cage ( 24 ) for each clamping body ( 22 ) one stop each ( 42 ) is provided which a movement distance of the clamping body ( 22 ) limited when tilting from the clamping position to the freewheeling position. Sprag freewheel ( 10 ) according to one of the preceding claims, characterized in that the clamping body ( 22 ) in the cage ( 24 ) are guided with play, so that the clamping body ( 22 ) and the cage ( 24 ) during the movement of the clamping bodies ( 22 ) do not slide between the clamping position and the free-running position. Sprag freewheel ( 10 ) according to one of the preceding claims, characterized in that the outer ring ( 14 ) a connecting rod eye ( 18 ) for connection to a connecting rod-like connecting element of a crank-CVT transmission. Sprag freewheel ( 10 ) according to claim 15, characterized in that the outer ring ( 14 ), in particular adjacent to the connecting rod eye ( 18 ), one or more stress reduction ports ( 19 ) having. Crank CVT transmission with a sprag freewheel ( 10 ) according to any one of the preceding claims.